Wakame (Undaria pinnatifida) modulates hyperphosphatemia in a rat model of chronic renal failure

In chronic renal failure, inorganic phosphate (Pi) retention speeds up the progression to end-stage renal disease. The current therapy for hyperphosphatemia in patients with chronic renal failure consists of dietary Pi restriction combined with administration of Pi binders, but each therapy has practical problems. Thus, the discovery of foods or nutrients that inhibit Pi absorption may be useful for the treatment of hyperphosphatemia. In the present study, we investigated whether wakame (Undaria pinnatifida) is a useful food for the prevention of hyperphosphatemia in a rat model of renal failure. Feeding a diet containing 5% wakame significantly decreased plasma and urinary Pi levels and increased the amount of fecal Pi. In addition, wakame significantly reduced plasma blood urea nitrogen and plasma Pi levels in 5/6 nephrectomized rats fed a high-Pi diet. Biochemical analyses showed that the reduction of intestinal Pi absorption is the main reason for the decrease in plasma Pi levels in rats fed a diet containing wakame. In addition, feeding alginic acid and fucoidan, major components of wakame fiber, was effective in reducing plasma Pi levels in normal rats. Finally, we concluded that wakame may be a useful food for the prevention of hyperphosphatemia in rodents.